every time I have a PS question, I simply go to google.com and type in "photoshop tutorial insert topic here" ie: photoshop tutorial lightning if I wanted to learn how to make my own realistic looking lightning. You'll get a ton of results!

To try to write an entire Photoshop tutorial is asking for a bit much....

There are literally TONS of books about it, and online resourses are huge, too. Just start by learning what each tool in the toolbox does, and then what each function in the menu bar does.

I'll offer you this tip in photoshop compositing, though:

Always duplicate the same lighting conditions in every element you are compositing. For instance, if you have a photo of a city that you are dropping Metroplex into, take the Metroplex toy outside at the same angle/time of day that the Cityscape picture is in and photograph it there. Then, when you put the photos tegether the color/light/shadows will match better.

create new layer.
select area to be recolor with with select marquee tool.
drop a color.
adjust layer setting accordingly. normal settings are either multiply, screen or overlay. alos play with the layer opacity.

create new layer.
select area to be recolor with with select marquee tool.
drop a color.
adjust layer setting accordingly. normal settings are either multiply, screen or overlay. alos play with the layer opacity.

I use the polygon lasso to select the area I want to re-color. Once selected there's several things you can do:

*Create a new layer, dump the desired color, change the layer blending mode.

*OR copy the selection, paste it exactly on top of the original, and then alter the copied sections color by going to edit/adjust/hue saturation. Check the "colorize" button and then slide hue, saturation, and brightness until the desired shade is reached.

*OR copy the selection, paste it exactly on top of the original, and then add a "color overlay" layer effect. Change the blending mode of the color overlay as needed.

Personally I do the "copy and then hue saturation" method the most.

One thing to watch out for: pay attention to contrast. Especially when going from a dark original color to a new lighter color. Crank up that contrast when needed (edit/adjust/brightness contrast). Tone it down when needed.